Groening has remained free pending the appeal and a decision on his fitness for prison. On Wednesday, Kathrin Soefker, a spokeswoman for prosecutors in Hannover, told news agency dpa they have rejected a defense application for a reprieve on serving the sentence.

She said a doctor considers Groening fit to go to prison so long as there's appropriate medical care. There's been no formal summons yet for him to start serving his sentence.

Groening's trial — 70 years after the liberation of Adolf Hitler's concentration camps — was likely to be one of Germany's last Nazi prosecutions. Germany has mounted a last push to bring Nazi criminals to justice, but the suspects and fugitives are aging and many have died.